Cooling system for heated calender rolls

ABSTRACT

A system for rapidly reducing the temperature of a heated roll used in calender or embossing machines. Water is mixed with and atomized in a stream of air and injected into the burner of the calender roll for impinging on the interior wall of the roll. The water absorbs the heat of the roll and is vaporized and exhausted at either end of the roll in the same manner as are exhaust combustion gases.

United States Patent Rauskolb Oct. 24, 1972 [54] COOLING SYSTEM FOR HEATED CALENDER ROLLS M w. Rauskolb, Haworth, NJ.

AIR

GAS I 3,119,603 l/l964 Schaab et al ..263/6 C Primary Examiner--Charles J. Myhre Attorney-Weingarten, Maxham and Schurgin [57] ABSTRACT A system for rapidly reducing the temperature of a heated roll used in calender or embossing machines. Water is mixed with and atomized in a stream of air and injected into the burner of the calender roll for impinging on the interior wall of the roll. The water absorbs the heat of the roll and is vaporized and exhausted at either end of the roll in the same manner as are exhaust combustion gases.

6 Claims, 3 Drawing Figures MAIN BURNER FUEL REGULATION FUEL REGULATION PILOT TEMPERATURE CONTROLLER T "l TEMP. SENSOR-M23 BURNER CONTROL AIR ATOMIZING AIR WATER .32 CONTROL AIR REGULATOR AIR lN4 33 ATOMIZING AIR REGULATOR 34 REGULATOR WATER 1 COOLING SYSTEM FOR HEATED CALENDER ROLLS FIELD OF THE INVENTION This invention relates in general to calenders and DISCUSSION OF THE PRIOR ART It is often necessary to heat one or more calender rolls in a calendering or embossing machine in order to achieve the desired results with the material which is being processed by the machine. Such materials may include paper, fabrics and plastic film and sheets. A significant problem associated with large metal calender rolls is that a great deal of time is required to make significant changes, especially reductions, in the surface temperature. Temperature changes are necessary when it is desired to use the machine for different materials or possibly when it is necessary to perform some maintenance or repair work on the machine. Cooling of such a roll is a particular problem because the heat reduction is principally accomplished by radiation. Rolls of this type generally have a surface polish which prevents rapid radiation and even with the addition of blowing cool air over the surface of the roll, it may take up to 36 hours to cool such a roll from 425F down to -275F, both temperatures being practical for different processes and different materials.

Calendering and embossing machines are very large and amount to a substantial capital expense for sheet product manufacturers. For this reason, such machines are used for as many different materials as possible. However, to change from a high temperature material to a somewhat lower temperature material renders the machine substantially useless for the number of hours involved for the temperature to drop to the desired level. This is, of course, a great waste of time and capital investment, causing a decrease in overall plant efficiency. One way in which plant efficiency may be increased, is to have more calender machines so that they may be operating at different temperatures and be available for different materials without the time waste associated with substantial temperature changes. However, it is evident that this is a very expensive and undesirable solution to the problem.

SUMMARY OF THE INVENTION 1 Broadly speaking, this invention comprises a uniquely modified heated calender roll system having a conventional interior burner throughout its length. Appropriate valves, controls and piping are added to provide a mixture of air and water to the burner so that, when the combustion mixture is shut off, water droplets may be applied directly to the interior surfaces of the roll through the burner to significantly speed up the process of cooling the roll. Through the use of such evaporational cooling which occurs when the water droplets impinging upon the interior wall of the roll change to vapor, the time to cool calender rolls may be reduced by as much as a factor of ten over the presently available procedure of awaiting temperature decrease by radiation. The term calender as used herein includes all machines of the type generally called calenders and embossers.

BRIEF DESCRIPTION OF THE DRAWING The objects, advantages and features of this invention will become apparent from the following detailed description when read in conjunction with the accompanying drawing, in which:

FIG. 1 is a simplified perspective view of a calender having a heated roll;

FIG. '2 is greatly enlarged partial perspective view of a portion of this invention showing some of the connections at the end of the burner of the heated roll of the calender shown in FIG. 1; and

FIG. 3 is a schematic diagram showing the calender roll cooling system of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The calender machine 11 shown in FIG. 1 is depicted in greatly simplified fashion for the purposes of this exposition. This machine has a resilient roll 12 and a heated roll 13 both rotatably mounted to support frame 14. The pressure applied between these two rolls may be adjusted by height adjusting means 15. Piping 16 is a simplified representation of the conduits necessary for providing the appropriate fluids and gases for heating and cooling of roll 13. Other conventional details, many of which arenot shown, which are normally associated with such a machine will not be described herein because they form no part of this invention.

The invention is clearly shown in FIGS. 2 and 3. Roll 13 is a heavy hollow cylinder having a burner 17 extending throughout its length. The roll may be as much as 132 inches long, 20 inches in diameter, have a steel wall thickness of eight inches and in internal axial bore four inches in diameter and weigh between 10,000 and 28,000 pounds. The burner may be of conventional construction and have a slot or a multiplicity of slits or tips for applying flame to the interior surface of the roll.

The burner normally occupies a portion of the cross section of the bore through the roll, there being normally at least one inch between the burner and the interior surface of the roll. This margin between bore and burner. permits exhaust gases and vapors to escape at either end of the roll. Burner 17 is provided with a connector element 18 at the end to which are connected the various air, fuel and water supplies as will be explained hereinbelow.

A combustion mixture comprised of air and fuel (normally natural gas but other fuels may be satisfactory) is supplied to connector 18 through a conventional main burner fuel regulator 21 which includes appropriate valves, gauges and controls and a mixer to properly combine air and fuel. Similarly, the com-v Connector 18has a conduit section 25 directly connected to the end of the burner 17, an input section 26 through which is applied the combustion mixture from main burner fuel regulator 21' and a drain leg 27 provided with a suitable drain cock 43 opposite the input side.

The cooling system of this invention is connected to the burner through the outer end of connector 18 by means of atomizer 31. Air is applied to the atomizer through control air regulator 32 and atomizing air regulator 33 while water is applied to the atomizer through regulator 34. The atomizer produces a fine water mist which is carried throughout the length of the burner by means of the combustion air which enters through input leg.26 of connector 18. It should be noted that combustion air is continuously supplied to the burner and when heat is desired, gas is added, while when cooling is desired the gas is turned off and the atomizing air and water are supplied through atomizer 31.

Atomizer 31 is a standard type fluidically controlled element subject to the controls of the air from regulator 32 appliedthrough conduit 35 as shown in FIG. 2. Atomizing air is provided'through conduit 36 and the cooling water is provided through conduit 37. The only function of the control air provided through conduit 35 is to turn the water on or off at atomizer 31. In one condition the control air permits water to pass through atomizer 31, whereupon the atomizing air atomizesthe water. into fine droplets. 7 After being atomized by atomizer 31, the water droplets pass through tube 42 to spray nozzle 41 at the end of burner 17. The finely divided water droplets will then be carried by the continuously flowing combustion air through the burner and out through the burner openings to impinge upon the inner surfaces of the hot roll. As the water droplets make contact with the hotroll, they are converted to vapor and exhausted out through the ends of the bore of the roll. Considering the great amount of heat necessary to vaporize water it is easily recognized how rapidly theheat may be removed from such a massive roll. The rate of cooling is controlled by variations made to the atomizing air and the waterapplied to atomizer 31. These two regulators may be tied together in a conventional manner so that the reduction in the amount of atomizing air supplied to atomizer 31 will cause a consequent proportional reduction in the amount of water and vice versa. When regulator 32 changes the air applied to atomizer 31 from one condition to another condition, the water is prevented from being-atomized and cannot enter burner 17.

It should be noted that this system, while described for only one end of a single heated roll calender, may be applied to both ends as shown in FIG. 3 and could equally be applied to a calender having multiple heated rolls. The application of the heating and cooling systems to both ends of one roll or to more than oneroll would employ structure identical to that already described for one end.

Because water is applied through atomizer 31, it is necessary to provide drip leg 27 in connector 18 for the collection of any excess water at that point. A drain cock 43 is provided at the bottom of drip leg 27 to drain the water therefrom when necessary.

A preferred embodiment of this invention has been disclosed and described in detail but it is quite likely that modifications, changes and improvements will occur to those skilled in the art which are within the scope of this invention. A possible modification is that a lock-out device may be employed so that either atomized water or combustion mixture may be applied to the burner but not both simultaneously. Any of several-well known techniques may be used for this purpose.

What is claimed is:

1. A calender machine comprising:

a support frame;

a first roll rotatably mounted to said frame;

a second roll rotatably mounted to said frame and adapted for longitudinal surface contact with said first roll, said second roll being made of metal and having an axial bore throughout its length;

a burner mounted to said frame and extending through said bore in said second roll, said burner being adapted to provide flame adjacent the surface of said bore along the length thereof;

means for providing a combustion mixture of fuel and air to said burner; and

means for-providing water mist to the walls of said bore through said burner.

2. The calender machine recited in claim l and further'comprising:

a connector at the end of said burner, the combustion mixture being applied to said burner through said connector; and a i an atomizer for converting waterv and air to water mist, said atomizer being coupled to said connector for applying said water mist to said burner.

3. The calender machine recited in claim 2 and further comprising:

a water pressure regulator;

an atomizing air regulator; and

a control air regulator;

wherein said atomizer has 'a water inlet port, an atomizing air inlet port and a control air port, said control air being adapted to alternatively permit and prevent the flow of water through said atomizer responsive to selective control of said control air regulator, atomizing air and water applied to said atomizer and controlled by said respective regulators creating said water mist.

- 4. The calender machinerecited in claim 3 further comprising:

a spray nozzle-located within the end of said burner;

and

a conduit for conveying said water mist from said atomizer through said connector to said spray nozzle.

5. The calender machine recited in claim 2 wherein:

said connector is formed with a drip leg for collection of the unevaporated water outside of said burner, said calender machine further comprising;

a drain cock connected to said drip leg for selective removal of water therefrom.

6. The calender machine recited in claim 2 wherein:

said combustion mixture providing means includes a main burner fuel regulator having selectively actuated fuel controls and a mixer for mixing fuel and air to form a combustion mixture, said main burner fuel regulator continuing to supply combustion air to said burner when said fuel is turned off;

said water mist being carried through said burner to the walls of said bore by the combustion air. 

1. A calender machine comprising: a support frame; a first roll rotatably mounted to said frame; a second roll rotatably mounted to said frame and adapted for longitudinal surface contact with said first roll, said second roll being made of metal and having an axial bore throughout its length; a burner mounted to said frame and extending through said bore in said second roll, said burner being adapted to provide flame adjacent the surface of said bore along the length thereof; means for providing a combustion mixture of fuel and air to said burner; and means for providing water mist to the walls of said bore through said burner.
 2. The calender machine recited in claim 1 and further comprising: a connector at the end of said burner, the combustion mixture being applied to said burner through said connector; and an atomizer for converting water and air to water mist, said atomizer being coupled to said connector for applying said water mist to said burner.
 3. The calender machine recited in claim 2 and further comPrising: a water pressure regulator; an atomizing air regulator; and a control air regulator; wherein said atomizer has a water inlet port, an atomizing air inlet port and a control air port, said control air being adapted to alternatively permit and prevent the flow of water through said atomizer responsive to selective control of said control air regulator, atomizing air and water applied to said atomizer and controlled by said respective regulators creating said water mist.
 4. The calender machine recited in claim 3 further comprising: a spray nozzle located within the end of said burner; and a conduit for conveying said water mist from said atomizer through said connector to said spray nozzle.
 5. The calender machine recited in claim 2 wherein: said connector is formed with a drip leg for collection of the unevaporated water outside of said burner, said calender machine further comprising; a drain cock connected to said drip leg for selective removal of water therefrom.
 6. The calender machine recited in claim 2 wherein: said combustion mixture providing means includes a main burner fuel regulator having selectively actuated fuel controls and a mixer for mixing fuel and air to form a combustion mixture, said main burner fuel regulator continuing to supply combustion air to said burner when said fuel is turned off; said water mist being carried through said burner to the walls of said bore by the combustion air. 